Method of position stamping a photo or video clip taken with a digital camera

ABSTRACT

A method of appending a position stamp to an image file of a photo or video clip taken with a digital camera having a GPS antenna and a GPS RF front-end including an analogue to digital converter for receiving GPS signals and outputting GPS signal samples together with a digital camera and computer for the same.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a method of appending a position stamp to animage file of a photo or video clip taken with a digital camera having aGPS antenna and a GPS RF front-end including an analogue to digitalconverter for receiving GPS signals and outputting GPS signal samples;and to a digital camera and computer for the same.

2. Description of Related Art

It is known to provide a digital camera having a GPS receiver whereinimage files generated by the digital camera are annotated or labelledwith data identifying the position of the camera at the time of captureas determined by the GPS receiver. For example, see U.S. Pat. No.6,269,446 or European patent application EP1189021A1.

BRIEF SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a method ofthe aforementioned type comprising the steps of (i) upon a user taking aphoto or video clip: (a) creating an image file containing that photo orvideo clip, and (b) sampling received GPS signals and storing those GPSsignal samples, e.g. in a file format, with an indication of the imagefile of the photo or video clip to which those GPS signal samplespertain; and (ii) subsequently processing the GPS signal samples toobtain a position fix and appending the position fix to the image file.

The inventors have realised that storing GPS signal samples with anindication of the image file of the photo or video clip to which thoseGPS signal samples pertain enables those GPS signal samples to beprocessed at leisure to determine a position fix and, thereafter, appenda position stamp to the image file. For example, they may be processedafter an intentional delay has elapsed; after the image file and GPSsignal samples have been uploaded to an external computer; or upondetecting the connection to the camera of an external power source(either automatically or after user confirmation of an automatic promptfor the same).

In particular, step (i) may be performed twice upon a user takingrespective first and second photo or video clips, prior to step (ii)being done for the first photo or video clip.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described, by way of example only,with reference to the accompanying FIGURE which shows, schematically, aPC connected to a digital camera including GPS receiver device, bothoperating in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the accompanying FIGURE, the PC is connected via a USB PCport and corresponding cable to a digital camera 10 which comprises aGPS front-end receiver (Rx) connected to a GPS antenna, an image sensor(IS) and memory (Mem), all under the control of a micro-controller μC.

When operative, the GPS receiver receives NAVSTAR SPS GPS signalsthrough its antenna and pre-process them, typically by passive bandpassfiltering in order to minimise out-of-band RF interference,preamplification, down conversion to an intermediate frequency (IF) andanalogue to digital conversion. The IF signal remains modulated, stillcontaining all the information from the available satellites. Theresultant GPS signal samples are then stored in the memory (Mem).

In accordance with the present invention, the digital camera and PC maygenerate a position stamped image file as illustrated in any of thefollowing example scenarios:

EXAMPLE 1

Upon a user in possession of the camera taking a photo, an image filecontaining that photo is created and stored in the memory. At the sametime, the GPS receiver receives and samples GPS signals and stores theresultant GPS signal samples in a data file format in the memorytogether with an indication of the image file to which the GPS signalsamples pertain.

Once the user returns home and connects the digital camera to the user'shome PC, the image file and corresponding GPS signal samples areuploaded to the PC. The GPS signal samples are then processed usingappropriate PC based GPS signal processing software and the PCs morepowerful processor to recover pseudorange information from which theposition of the digital camera when the corresponding photo was takencan be determined using conventional navigation algorithms. Such GPSsignal acquisition and pseudorange processing is well known, forexample, see GPS Principles and Applications (Editor, Kaplan) ISBN0-89006-793-7 Artech House. The position fix is then appended the imagefile.

EXAMPLE 2

As example 1 except that two or more photos are taken with correspondingimage files and GPS signal samples recorded prior to connection with thePC. Upon connection, both sets of GPS signal samples are processed andthe position fixes obtained appended to respective image files.

EXAMPLE 3

Instead of the GPS signal processing software being PC based, it may becamera based whereby GPS signal samples are processed only after anintentional delay has elapsed after the image file has been created andthe GPS signal samples stored. For example, one might post process theGPS signal samples in slow time, thereby minimising processor powerconsumption. Similarly, the GPS signal samples might be processed onlyafter detecting the connection of the camera to an external powersource.

Whilst the invention has been described in the context of NAVSTAR GPS,the all weather, spaced based navigation system developed and currentlyoperated by the US Department of Defense, it will be appreciated thatthe invention is equally applicable to other global positioning systemsincluding GLONASS and Galileo and hybrids thereof.

Finally, from a reading of the present disclosure, other modificationswill be apparent to persons skilled in the arts of GPS and digitalcameras which may involve features which are already known in thedesign, manufacture and use of GPS receivers, digital cameras andcomponent parts thereof and which may be used instead of or in additionto features already described herein.

1. A method of appending a position stamp to an image file of a photo orvideo clip taken with a digital camera having a GPS antenna and a GPS RFfront-end including an analogue to digital converter for receiving GPSsignals and outputting GPS signal samples, the method comprising thesteps of: (i) upon a user taking a photo or video clip: (a) creating animage file containing that photo or video clip, and (b) samplingreceived GPS signals and storing those GPS signal samples with anindication of the image file of the photo or video clip to which thoseGPS signal samples pertain; and (ii) subsequently processing the GPSsignal samples to obtain a position fix and appending the position fixto the image file.
 2. A method according to claim 1 wherein step (ii) isdone after an intentional delay has elapsed after step (i).
 3. A methodaccording to claim 1 further comprising the step of, after step (i) butbefore step (ii), uploading the image file and GPS signal samples to anexternal computer.
 4. A method according to claim 1 further comprisingthe step of, after step (i), detecting the connection to the camera ofan external power source whereupon step (ii) is done eitherautomatically or after user confirmation of an automatic prompt for thesame.
 5. A method according to claim 1 wherein step (i) is performedtwice upon a user taking respective first and second photo or videoclips, prior to step (ii) being done for the first photo or video clip.6. A method according to claim 1 wherein the GPS signal samples arestored in a file format.
 7. A digital camera comprising: a GPS antenna;a GPS RF front-end including an analogue to digital converter forreceiving GPS signals; said digital camera being configured so that upona user taking a photo or video clip: (a) an image file is createdcontaining that photo or video clip and (b) received GPS signals aresampled and the GPS signal samples are stored with an indication of thecreated image file to which said GPS signal samples pertain; and a GPSsignal processor to perform subsequent processing of the GPS signalsamples to obtain a position fix and append the position fix to theimage file.
 8. A digital camera according to claim 7 configured toprocess the GPS signal samples to obtain said position fix after anintentional delay has elapsed after said GPS signal samples are stored.9. A digital camera according to claim 7 configured to process the GPSsignal samples to obtain said position fix after detecting theconnection to the camera of an external power source eitherautomatically or after user confirmation of an automatic prompt for thesame.
 10. A digital camera according to claim 7 configured to allow saidimage file creation and said GPS signal sample storing to be performedtwice upon a user taking respective first and second photo or videoclips prior to processing the GPS signal samples to obtain said positionfix and appending the position fix to the image file of the first photoor video clip.
 11. A digital camera according to claim 7 configured toupload the image file and GPS signal samples to an external computer.12. A digital camera according to claim 11 configured to allow saidimage file creation and said GPS signal sample storing to be performedtwice upon a user taking respective first and second photo or videoclips prior to uploading the image files and GPS signal samples to saidexternal computer.
 13. A digital camera according to claim 7 wherein theGPS signal samples are stored in a file format.
 14. A computercomprising a processor and receiver, and configured to: (a) receivethrough the receiver an image file containing a photo or video clip, GPSsignal samples and an indication of the corresponding image file towhich the GPS signal samples pertain by virtue of having been sampledwhen the corresponding photo or video clip was taken; (b) process byoperation of the processor the GPS signal samples to obtain a positionfix; and (c) append the position fix to the corresponding image file byoperation of the processor.